EasyRelation

<dependency>
    <groupId>cn.easii</groupId>
    <artifactId>easy-relation-spring-boot-starter</artifactId>
    <version>1.1.0</version>
</dependency>

@Data
public class Order {

    private String orderId;

    private String username;

    @Relation(provider = RelationIdentifiers.getUserByUsername, targetField = "nickName",
        condition = {@Condition(field = "username")})
    private String nickName;

}

@Component
public class UserInfoDataProvider implements DataProvideService {

    @DataProvider(RelationIdentifiers.getUserByUsername)
    public User getUserByUsername(UserQueryReq req) {
        // 这里可以从任意来源获取值
        if ("admin".equals(req.getUsername())) {
            final User user = new User();
            user.setUsername("admin");
            user.setNickName("管理员");
            return user;
        }
        return null;
    }

}

@SpringBootTest
class InjectRelationTest {

    @Autowired
    private InjectRelation injectRelation;

    @Test
    void quickStart() {
        Order order = new Order();
        order.setOrderId("2f453910375641648ab3a2fc6e3328ef");
        order.setUsername("admin");
        injectRelation.injectRelation(order);
        System.out.println(order);  // Order(orderId=2f453910375641648ab3a2fc6e3328ef, username=admin, nickName=管理员)
        Assert.equals(order.getNickName(), "管理员");
    }

}